Closure counterbalance

ABSTRACT

Two telescopically related tubes to be secured at their outer ends to a closure and closure support, respectively. A compression spring within the tubes urges them apart and stop means limit the extension of the device. In one form, a helical torsion spring between the tubes is fixed at one end to the outer tube and normally contracts to frictionally grip the inner tube. A rotatable sleeve is connected to the other end of the spring so it can be manually expanded to release its grip on the inner tube.

United States'Patent 91 Tabor [4 1 Jan. 23, 1973 [54] CLOSURECOUNTERBALANCE [75] Inventor: Paul C. Tabor, Clawson, Mich. I

[73] Assignee: Meteor Research Limited, Roseville,

Mich.

[22] Filed: Nov. 7, 1969 [21] Appl. No.: 874,798

[52] U.S. C1. ..l6/76, 188/67, 248/354 [51] Int. Cl. ..E05f U118 [58]Field of Search ..l6/66, 72, 49, 71, 140, 65, 16/1, 85, 190, 193;74/531; 188/67, 102;

[56] References Cited UNITED STATES PATENTS 1,999,844 4/1935 McElroy..248/414 2,957,187 10/1960 Raia ..5/3l7 1,480,788 1/1924 Sordillo....248/4l4 2,797,119 6/1957 Hollansworth ....292/275 3,230,595 1/1966Kedem ..188/67 3,249,180 5/1966 Torossian ..188/67 3,278,979 10/1966Clement ..16/66 FOREIGN PATENTS OR APPLICATIONS 857,756 1/1961 GreatBritain 1,249,465 11/1960 France ..l88/l02 464,202 12/1951 Italy..188/102 Primary Examiner-Bobby R. Gay Assistant ExaminerGarry MooreAtt0rney--Bacon & Thomas [5 7] ABSTRACT Two telescopically related tubesto be secured at their outer ends to a closure and closure support,respectively. A compression spring within the tubes urges them apart andstop means limit the extension of the device. In one form, a helicaltorsion spring between the tubes is fixed at one end to the outer tubeand normally contracts to frictionally grip the inner tube. A rotatablesleeve is connected to the other end of the spring so it can be manuallyexpanded to release its grip on the inner tube,

9 Claims, 9 Drawing Figures PATENH-Inmzs 1975 3.71 1. 892

SHEET 1 UF 2 INYEN'TOR. 34m 6 7250/? CLOSURE COUNTERBALANCE BACKGROUNDOF THE INVENTION This invention is in the field of counterbalancingdevices and particularly such devices having means for locking thecounterbalanced member in a desired position.

In many instances it is desirable to counterbalance the weight of amovable closure and to hold the closure safely in its open position.Such closures as automobile hoods, trunk lids, tail gates, etc. arerelatively heavy, must be counterbalanced and should be able to belocked in open position to'protect persons thereunder. Priorcounterbalancing devices have been quite bulky and expensive and lockingmeans used have not been completely reliable.

SUMMARY OF THE INVENTION The present invention comprises generally atelescopically extensible member or strut having a compression springtherein to resiliently urge the device to elongate, and stop means tolimit elongation. The invention also contemplates manually andselectively operable locking means to lock the telescoping partstogether to thus define a temporarily rigid and substantiallyinextensible strut for securely holding a closure in fully or partlyopen position while still being able to be forcibly collapsed to preventdamage to the strut and/or the closure.

The disclosure is specifically directed to such a device as contemplatedfor automotive use but it will be obvious that its application is moregeneral, for example, for doors, hatches, windows, freezer or chest lidsand many others.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing onetype of use for the present invention;

FIG. 2 is a longitudinal sectional view taken along the line 22 of FIG.1;

FIG. 3 is a further enlarged sectional view of the midportion of FIG. 2;

FIG. 4 is a transverse sectional view taken on the line 4-4 of FIG. 3;

FIG. 5 is a side elevational view, with parts being broken away, of afurther embodiment of the invention;

FIG. 6 is a longitudinal sectional view taken substantially on the line6-6 of FIG. 5;

FIG. 7 is an enlarged sectional view of the intermediate portion of FIG.6;

FIG. 8 is an enlarged transverse sectional view taken on the line 8-8 ofFIG. 5; and

FIG. 9 is a transverse sectional view taken on the line 9-9 of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates acontemplated use for the present invention wherein a vehicle 2, shown indotted line, is provided with a conventional hinged hood 4. Thecounterbalance 6 of the present invention may be mounted as indicated inFIG. 1 and serves to counterbalance the weight of the hood to render iteasy to lift to open position and to normally hold the same in its openposition. While FIG. 1 illustrates a specific use for the device, it

is to be understood that this is merely illustrative and that thecounterbalance to be described may be employed in many diverse otherenvironments.

Referring now to FIG. 2 to 4, the counterbalance strut 6 comprises apair of telescopic tubular members, a large outer tube member 8 and asmaller or inner tube member 10. At their inner ends the tube members 8and 10 are telescopically related, as shown and their relative diametersare such that an annular space 12 exists between the tubular members. Aplug member 14 fits within the upper end of the tube 8 and is securedthereto, such as by the rounded bead 16 swaged into a correspondinggroove in the plug and the plug defines an ear 18 having an opening 20therethrough. Preferably, an elastomeric grommet 22 is positioned in theopening 20 for the reception of a suitable bolt 24 for securing the plug14 to a closure or supporting structure therefor. The grommet 22compensates for any slight misalignment between the bolt holes in thesupporting structures and the eyelets in the plugs.

A plug 26, similar in all respects to the plug 14, is secured to theouter end of the inner tubular member 10 and is provided with theopening and grommet already described.

As is apparent from FIG. 2 of the drawings, the upper ear 18 is thickerthan the lower ear and is of greater I sectional area around theopenings 20 than the area of the lower ear. Thus, it is obvious that thelower ear is much weaker than the upper, this being a desirable featureto predetermine which ear will fail upon undue shock loads being appliedto the device. Knowing that the predetermined ear will fail first, thatone can be so positioned in the final assembly with a vehicle thatfailure of that ear and the resultant sudden expansion of the devicewill result in the energy of the expansion being directed in a manner sothat persons nearby will not be injured.

It is further to be noted that the grommets 22 in both ears extendoutwardly beyond the opposite faces of those ears and serve to space thesame from the heads of the mounting bolts and the adjacent vehiclestructure. Thus, the grommets provide limited universal pivotal movementbetween the counterbalance device and the parts of the vehicle to whichit is attached. This not only permits mounting to parts that aresomewhat misaligned but also permits universal tilting where the axis ofmounting to the closure does not always remain parallel to the axis atthe other end, during closure movement.

Within the tubular members 8 and 10 is a compression spring 28, reactingagainst the plugs 14 and 26 to thereby tend to elongate thecounterbalance strut. As will be obvious, from inspection of FIG. 1, thespring 28 serves effectively to counterbalance the weight of the hood 4.

The inner end of the outer tube 8 is reduced in diameter, as shown at30, to about the outer surface of the member 10 so as to provide a freesliding fit thereon. The outer member 8 is also provided with aninwardly extending abutment in the form of an annular rib 32, rolled orotherwise formed therein, spaced from the end 30 and extending inwardlyto about the outer surface of the member 10. The inner end of the member10 is flared outwardly, as at 34 and is provided with a terminalcylindrical portion (as shown) of greater diameter than the tube 10,substantially into sliding engagement with the inner surface of member8. It will be apparent that the abutment rib 32 serves as a stop meansto limit elongation of the counterbalance device under the influence ofspring 28 and that the flared end 34 and its terminal cylindricalportion, the rib 32 and the reduced end portion 30 all function asslidable guiding means between the members to maintain them in axialalignment. It is to be further noted that the distance between reducedend 30 and rib 32 is a substantial distance, thereby firmly aligning themembers against undue tilting and constituting an efficient linearguide.

Referring now to FIGS. -9, a second form of the invention is showntherein. Similar parts to those shown in FIGS. 2-4 bear the samereference numerals. In this embodiment, an outer tube 36 is providedwith a closure plug 38 at one end, similar to the plug 14 of FIG. 2,except that the car 40 is centrally located rather than laterallyoffset. In like manner the inner tubular member 42 is provided with anend plug 44, likewise having its car 46 centrally located. Within thetelescopically related tubular members 36 and 42 is a pair ofcompression springs 48 and S0, concentrically arranged with the outerspring 48 being held in centered relation within the larger tube 36 by asuitable boss 52 on the plug 38. lnwardly from its inner end the outermember 36 is provided with inwardly directed abutments 54, similar tothe rib 32 of FIG. 2, but comprising spaced inwardly deformed portionsrather than a continuous rib (see FIG. 9). The projections 54 functionin a manner similar to the rib 32 and are engaged by the flared end 56of the inner tubular member 42 to limit extension of the counterbalance.The innermost end of the outer tubular member 36 is turned inwardly todefine a radial flange 58 (see FIG. 7) having a notch 60 therein. A ring62 of suitable plastic material is positioned against the flange 58, inthe annular space 12 to serve as centering means for the tubular membersand to function somewhat as an anti-friction bearing member. The ring 62is not continuous but is split at 64 (see FIG. 8) with its ends spacedapart somewhat and with the space 65 therebetween in alignment with thenotch 60 in flange 58.

Within the space 12 is a helical torsion spring 66, formed preferably ofrectangular wire, having a hooked end portion 68 (see FIG. 5) extendingbetween the ends of the split ring 62 and through the notch 60 of flange58 to thus anchor one end of the torsion spring to the outer tubularmember 36. The helical torsion spring 66 is so constructed that itsinner diameter, when relaxed, is somewhat less than the outer diameterof the inner tubular member 42 and thus when assembled in the mannershown, the spring 66 normally tends to contract into tight frictionalengagement with the tubular member 42.

The upper end of the torsion spring 66, as seen in FIG. 7, is turnedoutwardly, as shown at 70, and extends through a slot 72 in the outertubular member 36 (see also FIG. 5). The end 70 extends outwardlythrough the slot 72 and through an opening 74 in a sleeve member 76,loosely and rotatably surrounding the outer tubular member 36.

FIG. 5 illustrates the general shape of the slot 72 as being generallycircumferential but having an end portion 78 extending axially anddefining a shoulder 80.

The sleeve 76 may obviously be manually manipulated by rotating the samein a direction to unwind the torsion spring 66, thus increasing itsdiameter and causing it to release its frictional grip on the innertubular member 42. When the sleeve 76 is rotated from the position shownin FIG. 5 to move the end of spring 66 to the left, this unwinding orreleasing action occurs. Obviously, sleeve 76 and the end 70 of thespring can be moved axially. somewhat and sufficiently to ride over thehump portion 82 of the slot 72 and end 70 can then be positioned behindthe shoulder 80 to hold the spring in its unwound position, leavingthecounterbalance free to extend or contract without restraint from thetorsion spring. Obviously, the sleeve 76 may then be manuallymanipulated to remove the end 70 of the spring from the shoulder 80 andpermit the spring 66 to again contract into tight frictional grippingrelationship to the inner tubular member 42. Since the spring 66 isfixed at one end to the outer tubular member 36, when it frictionallygrips the inner tubular member in the manner described, it serves as afriction lock preventing telescopic extension or compression of thecounterbalancing device. However, if the strut is so locked in itsextended position, to hold hood 4 open, for example, undue force orpressure on the hood will cause the spring 66 to slip relative to tube42 and thus prevent damage to the hood and/or strut.

While a limited number of specific embodiments of the invention havebeen shown and described, the same are merely illustrative of theprinciples involved and other forms will be apparent to those skilled inthe art.

I claim:

1. A counterbalance for a movable closure on a structure comprising; apair of tubular members, with their inner ends in coaxial telesc'opedand sliding relation; means at the outer end of each member defining anabutment and comprising securing means for securing said ends to aclosure and a closure supporting structure, respectively; compressionspring means within said tubular members, reacting at its opposite endsagainst said abutments whereby to urge said tubular members apart; andcooperating stop means on said tubular members for limiting relativeoutward movement thereof, the relative diameters of said tubular membersbeing such as to provide an annular space therebetween; said stop meanscomprising an annular inwardly extending integral shoulder on the outerof said members, spaced from the inner end thereof, and an outwardlyflared inner end on the inner member engageable with said integralshoulder; at least the inner end of said outer member being of reduceddiameter to slidably engage the outer surface of the inner member, saidsecuring means each comprising a longitudinally extending ear having anopening therethrough, an elastomeric grommet in each opening, and aportion of said grommet spacing said cars from connected structures toprovide limited universal movement relative thereto; one of said earsbeing of less sectional area than the other whereby said one car willfail first when said counterbalance is subjected to undue force.

2. A counter balance as defined in claim 1 including selectivelyoperable locking means in said annular space for locking said tubularmembers against relative telescoping movement.

3. A counterbalance as defined in claim 2 wherein said locking meanscomprises a helical torsion spring surrounding the inner of said tubularmembers and of a diameter to normally contract into tight frictionalengagement therewith; one end of said spring being secured to the outermember; and manually operable means, accessible from the exterior of theouter member, for moving the other end of said spring in a direction toincrease the diameter thereof to thereby release its frictional grip onthe inner member.

4. A counterbalance as defined in claim 3 including means retaining saidspring at the inner end of the outer member.

5. A counterbalance as defined in claim 4 wherein said one end of saidtorsion spring is secured to said outer member at the inner end thereof;said manually operable means comprising a rotatable sleeve around theouter member and having an opening therethrough; a generallycircumferential slot through the inner tubular member radially inwardlyof said opening, the said other end of said spring extending generallyradially outwardly and through said slot and opening.

6. A counterbalance as defined in claim 7 wherein one end of said slotcomprises an axially extending portion adapted to engage and hold saidoutwardly bent end of said spring when said spring is radially expanded.

7. A counterbalance as defined in claim 1 wherein said elastomeric meansfor spacing said ears comprise end portions of said grommets extendingoutwardly of opposite sides of said ears.

8. A counterbalance as defined in claim 1 wherein said compressionspring means comprises at least two compression springs, one axiallywithin the other.

9. A counterbalance as defined in claim 1 including an integralcylindrical axial extension at the outer periphery of said flared innerend on the inner member.

1. A counterbalance for a movable closure on a structure comprising; apair of tubular members, with their inner ends in coaxial telescoped andsliding relation; means at the outer end of each member defining anabutment and comprising securing means for securing said ends to aclosure and a closure supporting structure, respectively; compressionspring means within said tubular members, reacting at its opposite endsagainst said abutments whereby to urge said tubular members apart; andcooperating stop means on said tubular members for limiting relativeoutward movement thereof, the relative diameters of said tubular membersbeing such as to provide an annular space therebetween; said stop meanscomprising an annular inwardly extending integral shoulder on the outerof said members, spaced from the inner end thereof, and an outwardlyflared inner end on the inner member engageable with said integralshoulder; at least the inner end of said outer member being of reduceddiameter to slidably engage the outer surface of the inner member, saidsecuring means each comprising a longitudinally extending ear having anopening therethrough, an elastomeric grommet in each opening, and aportion of said grommet spacing said ears from connected structures toprovide limited universal movement relative thereto; one of said earsbeing of less sectional area than the other whereby said one ear willfail first when said counterbalance is subjected to undue force.
 2. Acounter balance as defined in claim 1 including selectively operablelocking means in said annular space for locking said tubular membersagainst relative telescoping movement.
 3. A counterbalance as defined inclaim 2 wherein said locking means comprises a helical torsion springsurrounding the inner of said tubular members and of a diameter tonormally contract into tight frictional engagement therewith; one end ofsaid spring being secured to the outer member; and manually operablemeans, accessible from the exterior of the outer member, for moving theother end of said spring in a direction to increase the diameter thereofto thereby release its frictional grip on the inner member.
 4. Acounterbalance as defined in claim 3 including means retaining saidspring at the inner end of the outer member.
 5. A counterbalance asdefined in claim 4 wherein said one end of said torsion spring issecured to said outer member at the inner end thereof; said manuallyoperable means comprising a rotatable sleeve around the outer member andhaving an opening therethrough; a generally circumferential slot throughthe inner tubular member radially inwardly of said opening, the saidother end of said spring extending generally radially outwardly andthrough said slot and opening.
 6. A counterbalance as defined in claim 7wherein one end of said slot comprises an axially extending portionadapted to engage and hold said outwardly bent end of said spring whensaid spring is radially expanded.
 7. A counterbalance as defined inclaim 1 wherein said elastomeric means for spacing said ears compriseend portions of said grommets extending outwardly of opposite sides ofsaid ears.
 8. A counterbalance as defined in claim 1 wherein saidcompression spring means comprises at least two compression springs, oneaxially within the other.
 9. A counterbalance as defined in claim 1including an integral cylindrical axial extension at the outer peripheryof said flared inner end on the inner member.